Field of the Invention
The present invention relates to an electrostrictive element.
Description of the Related Art
It is known that when at least one surface of a dielectric film composed of an elastomer is connected with an electrode to which voltage is applied, the dielectric film receives a compressive force by Maxwell stress (piezoelectric opposite effect) from interfacial polarization caused by an electrostatic force, and contracts in a thickness direction and expands in a lateral direction (direction orthogonal to the thickness direction). In recent years, it has been considered to use as a piezoelectric element an electrostrictive element that comprises a dielectric film and an electrode, and operates in accordance with that principle.
As such a piezoelectric element, a piezoelectric element is hitherto known that comprises a dielectric film composed of an elastomer, a first electrode layer capable of expanding and contracting and formed on at least one surface of the dielectric film, a piezoelectric crystal thin film capable of expanding and contracting and formed on the first film electrode, and a second electrode layer capable of expanding and contracting and formed on the piezoelectric crystal thin film (for example, see Japanese Patent Laid-Open No. 2005-347364).
However, the piezoelectric element has a drawback in which the dielectric film may easily break down at a portion that has become thinner receiving a compression force due to Maxwell stress when voltage is applied to the first electrode layer, because the first electrode layer is formed over an entire surface of the dielectric film composed of the elastomer. The drawback may arise in cases other than using the electrostrictive element as a piezoelectric element.